1. Field of the Invention
The invention relates to a push-button telephone having means for changing from a normal operating mode to a restricted operating mode in which at least one pre-programmed function is assigned to at least one push-button, the operation of the other push-buttons being deactivated.
The invention likewise relates to a device intended to be adapted to such a telephone, said device comprising at least one push-button called visible push-button which is associated to a pre-programmed push-button of said telephone when said device is adapted to said telephone.
The invention finally relates to telephone equipment having such a push-button telephone and such a device.
The invention has highly significant applications notably in the field of mobile telephony.
2. Background of the Invention
Such equipment is described in European Patent Application n.degree.0 354 367 A2, filed Jul. 11, 1989 by SANYO ELECTRIC CO. This equipment has a cover plate for masking the keyboard of the telephone and mechanical locking means for locking this cover plate on the telephone. By adapting the cover plate to the body of the telephone, a mode change key of the telephone is depressed, so that the telephone automatically changes from the normal operating mode to the restricted operating mode. In other words, the telephone is maintained in the restricted operating mode by mechanical means, which can be mischievously used.